Can you imagine having a photo of everyone in your family for two generations at the same location at about the same age? What an awesome collection that must be!
Well, our family photo traditions aren't that old, but they're good nonetheless. We attend a Swedish party at Christmastime called a Julefest, where we have someone take a picture of all of us in front of the giant Christmas tree that we dance around at the party. It's great to look through and see us grow from a family of 2 to 3 to more.
It's never too late to start a tradition. Choose a time when you can get a photo of your family at the same time each year (holidays are good, since you're usually together and the camera is probably handy), and make an effort to get someone to take your picture together. It's not the same as a professional family portrait, but it's not supposed to be. It's just another little record of you and your family as you grow and progress.
Make an extra-special effort to take traditional family photographs. You won't regret it!